Entwicklung von Simulations- und Analysemethoden zur Modellierung von Störkräften im Rahmen der Satellitenmission MICROSCOPE

In fundamental physics, a condition for the validity of the general theory of relativity is constantly being put to test: the weak equivalence principle. The satellite mission MICROSCOPE (MICRO-Satellite a trainee Compense pour la Observation du Principe da Equivalence) shall set a new milestone, aiming at a measurement result with an accuracy of 1e-15 and thus improving previous results by two orders of magnitude. The experiment is carried out with a differential accelerometer in which two test masses of different material are held on the same trajectory by means of electrostatic forces. Therefor the mass centres of these test masses, which are concentric hollow cylinders, must coincide. Any difference in the required forces would indicate a violation of the weak equivalence principle. The desired measurement accuracy places high demands both on the measuring instrument and on the satellite, which must ensure undisturbed environmental conditions for the experiment. In order to avoid material deformation, high temperature stability is required. In addition, the satellite should protect the experiment from external disturbing forces resulting from its interaction with environmental conditions in space. For this purpose, a special attitude control system is used, which compensates for these non-gravitational forces and thus ensures a purely gravitational trajectory. The MICROSCOPE data analysis is a very complex process, as a large number of possible error sources must be taken into account including the non- gravitational forces which act on the satellite. Their influence on the measurement result cannot be completely excluded. The modelling of these disturbing forces is a central topic of this work. For this purpose, a calculation method has been implemented that can take into account complex satellite geometries by decomposing the surface using finite elements. This method enables the assignment of different material properties and the affected area can be very well determined. The calculation of the disturbance forces requires the time-dependent calculation of the satellitea s orbit and attitude. For this purpose, a simulation tool is used, which was in part developed in the framework of this work. Furthermore an analysis tool that is used to process and analyse MICROSCOPE measurement data was designed. It is used in conjunction with the disturbance force simulation and analysis to support the evaluation process of the MICROSCOPE data. In addition, the analysis tool is used to validate simulation results

Boradacre City and Zwischenstadt.

Kann man von der Broadacre City noch etwas lernen? Frank Lloyd Wrights Broadacre City ist, neben der Ville Radieuse und der Gartenstadt, das zentrale Stadtmodell der Moderne. Wright formulierte mit der Broadacre City eine radikale Dezentralisierung der Stadt. Damit ist es das umstrittenste und gleichzeitig das realistischste der drei Stadtmodelle. Die deutsche Debatte um die Zwischenstadt, die 80 Jahre nach Wright an der Gestaltung der nun real entstandenen dezentralen Stadtlandschaft arbeitet, kann über die Wiederentdeckung Wrights geschärft werden. Die Broadacre City ist das historische Fundament der Zwischenstadtdebatte, mit einem Erfahrungsschatz von rund 600 Entwürfen und 400 gebauten Projekten. Die vorliegende Arbeit ist ein systematischer Vergleich der Broadacre City und der Zwischenstadt. Sie erforscht Parallelitäten und zeigt auf, was wir heute noch von Frank Loyd Wright über die Gestaltung moderner Stadtlandschaften lernen können.What can be learned from Broadacre City? Besides the Ville Radieuse and the Garden City Frank Lloyd Wrights Broadacre City is the main city model of modernity. Wrights Broadacre City is a model for a radical decentralization of the city. For this reason it is the most controversial as well as the most realistic city model. The German debate on the Zwischenstadt deals with the design of contemporary forms for decentralized urban landscapes that came to reality 80 years after Wright. By re-discovering Wright the German debate can be enhanced. Broadacre City is the historic base of the Zwischenstadt debate with a pool of experience of about 600 design schemes and 400 realized projects. This work is a systematic comparison of the Broadacre City and the Zwischenstadt. It is a research on their parallels showing what can be learned today from Frank Lloyd Wright for the design of modern urban landscapes

The GbsR Family of Transcriptional Regulators: Functional Characterization of the OpuAR Repressor

Accumulation of compatible solutes is a common stress response of microorganisms challenged by high osmolarity; it can be achieved either through synthesis or import. These processes have been intensively studied in Bacillus subtilis, where systems for the production of the compatible solutes proline and glycine betaine have been identified, and in which five transporters for osmostress protectants (Opu) have been characterized. Glycine betaine synthesis relies on the import of choline via the substrate-restricted OpuB system and the promiscuous OpuC transporter and its subsequent oxidation by the GbsAB enzymes. Transcription of the opuB and gbsAB operons is under control of the MarR-type regulator GbsR, which acts as an intracellular choline-responsive repressor. Modeling studies using the X-ray structure of the Mj223 protein from Methanocaldococcus jannaschii as the template suggest that GbsR is a homo-dimer with an N-terminal DNA-reading head and C-terminal dimerization domain; a flexible linker connects these two domains. In the vicinity of the linker region, an aromatic cage is predicted as the inducer-binding site, whose envisioned architecture resembles that present in choline and glycine betaine substrate-binding proteins of ABC transporters. We used bioinformatics to assess the phylogenomics of GbsR-type proteins and found that they are widely distributed among Bacteria and Archaea. Alignments of GbsR proteins and analysis of the genetic context of the corresponding structural genes allowed their assignment into four sub-groups. In one of these sub-groups of GbsR-type proteins, gbsR-type genes are associated either with OpuA-, OpuB-, or OpuC-type osmostress protectants uptake systems. We focus here on GbsR-type proteins, named OpuAR by us, that control the expression of opuA-type gene clusters. Using such a system from the marine bacterium Bacillus infantis, we show that OpuAR acts as a repressor of opuA transcription, where several compatible solutes (e.g., choline, glycine betaine, proline betaine) serve as its inducers. Site-directed mutagenesis studies allowed a rational improvement of the putative inducer-binding site in OpuAR with respect to the affinity of choline and glycine betaine binding. Collectively, our data characterize GbsR-/OpuAR-type proteins as an extended sub-group within the MarR-superfamily of transcriptional regulators and identify a novel type of substrate-inducible import system for osmostress protectants

High precision orbit simulations for geodesy and fundamental physics missions

Orbit propagation including detailed environment models as well as system models is the basis for generating mock data sets for developing appropriate data analysis procedures in case of scientific and geodesy space missions. They allow to determine in virtual space the sensitivity of involved instruments and, furthermore, they help to optimize mission scenarios before their final design. It has been shown that the best gravitational redshift test is only possible if the correct modeling of the solar radiation pressure as well as interactions with magnetic fields and temperature effects are included in the data analysis process. Additionally, high precision simulations allow for the calibration of instruments in preparation for data analysis procedures, e.g. accelerometers on board of the GRACE satellites. The HPS (Hybrid Simulation Platform for Space Systems) developed from DLR and ZARM, University of Bremen, deals with all of these aspects. As a modular and generic tool it can be adapted to various scenarios of mission concepts and layouts. This talk will present examples of the usage of HPS in the context of instrument calibration, orbit propagation for studying the environmental influences on the satellite's orbit, and data analysis improvement on behalf of mock data sets

AOCS for future multi-satellite geodesy missions

Missions like GRACE and GRACE-FO have successfully established a continuous time series of data for Earth gravity field estimation. The continuous observation of Earths gravitational field is essential for the understanding of Earths mass transportation and climate change. Since GRACE-FO is already in service and the demand of more accurate data series arises, new Mission concepts need to be investigated to guarantee the continuation of the data time series and to increase the accuracy of Earths gravity field estimation. The German Aerospace Center (DLR) Institute for Satellite Geodesy and Inertial Sensing and the ZARM, University of Bremen are developing a Multi-Purpose Space Mission Simulator in the scope of the DFG Collaborative Research Center 1464 TerraQ. The simulation platform is capable of modelling for the atmospheric, magnetic, radiative, and gravitational environment in orbit and their coupling into system and sensor-specific effects. This work focuses on extending the simulation environment with an attitude control system to investigate next-generation gravimetry mission (NGGM) concepts with multiple satellites. The attitude control system should be modeled in three parts: Sensors, State Estimator and Controller, and Actuators. The aim is to model a realistic attitude control system. Thus, the performance of different satellite constellation approaches, such as pendulum orbits, bender orbits, and swarm constellations can be examined with the help of the simulator. Requirements for the AOCS subsystem will be derived to evaluate the feasibility of such mission concepts and sensors. This paper presents the current status of the research

Investigation of future geodesy mission concepts for their feasibility and requirements to the AOCS subsystem

Missions like GRACE and GRACE-FO have successfully established a continuous time series of data for Earth gravity field estimation. The continuous observation of Earths gravitational field is essential for the understanding of Earths mass transportation and climate change. Since GRACE-FO is already in service and the demand of more accurate data series arises, new Mission concepts need to be investigated to guarantee the continuation of the data time series and to increase the accuracy of Earths gravity field estimation. The German Aerospace Center (DLR) Institute for Satellite Geodesy and Inertial Sensing, as well as ZARM University of Bremen, is developing a simulation environment called the Hybrid Simulation Platform for Space Systems (HPS) to examine future geodesy satellite mission concepts. The simulation platform is capable of modelling for the atmospheric, magnetic, radiative, and gravitational environment in orbit and their coupling into system and sensor-specific effects. This work focuses on next-generation gravimetry mission (NGGM) concepts with multiple satellites and different satellite constellation approaches, such as pendulum orbits, bender orbits and swarm constellations, being examined with the help of the HPS simulator. In addition, new quantum sensors are considered to measure Earths gravitational field which put increased requirements on the AOCS subsystem, especially when considering drag-free control concepts. Requirements for the AOCS subsystem will be derived to evaluate the feasibility of such mission concepts and sensors. In parallel, collaborations with experts in orbit propagation and quantum sensors are being established within the scope of the German Collaborative Research Center TerraQ focusing on the improvement of Gravity field determination both on ground and space level. This paper presents the current status of the research

Development of a virtual environment for quantum technologies on satellite based next-generation gravimetry missions

The success of GRACE-FO and its predecessors has demonstrated to the scientific community the benefits of satellite gravimetry for monitoring mass variations on the Earth’s surface and its interior. However, the demand for increasingly higher spatial and temporal resolution of gravity field solutions has brought into focus the need for next-generation gravimetry missions (NGGMs). To this end, the German Aerospace Center (DLR) has established the Institute for Satellite Geodesy and Inertial Sensing, which investigates the potential of quantum technologies for NGGMs. Currently, quantum sensors for gravity field satellite missions are being developed, which include cold atom interferometry (CAI) gradiometers and optical clocks. In addition, quantum accelerometers and quantum inertial sensors are being studied for the application on satellites. NGGM concepts are analyzed using the Hybrid Simulation Platform for Space Systems (HPS) developed by ZARM (University of Bremen) and DLR. With the adaptation of HPS for the French MICROSCOPE mission, HPS was already capable of simulating the dynamics of the satellite and its test masses on a helio-synchronous orbit in an altitude of 700 km. The simulation included environmental models for the atmosphere, magnetic field, radiation, and gravity field, as well as a detailed model of the on-board capacitive sensors. Efforts have been made to extend the simulation platform to include quantum sensors. This introduces new challenges for pointing accuracy and noise determination, which place more stringent requirements on the computation of environmental disturbances in lower orbits suitable for NGGMs. Therefore, satellite vibration and thermal models are being investigated for use in HPS, with the goal of providing a complete testbed for quantum technologies in gravimetry missions. This paper presents the current status of the research

Reference mirror misalignment of cold atom interferometers on satellite-based gravimetry missions

The success of GRACE-FO and its predecessors has demonstrated the benefits of satellite gravimetry for monitoring mass variations on the Earth’s surface and its interior. However, the demand for increasingly higher spatial and temporal resolution of gravity field solutions has brought into focus the need for next-generation gravimetry missions (NGGMs). Therefore, we investigate the hybridization of electrostatic accelerometers (E-ACC) with cold atom interferometers (CAI), which can reduce the instrumental error contribution of the E-ACC, e.g. by enabling in-flight estimation of E-ACC bias parameters, and reduce systematic effects in gravity field solutions by proving drift free measurements. However, these sensors introduce more stringent requirements on the computation of environmental disturbances in lower Earth orbits, as the alignment of the CAI’s reference mirror has to be controlled precisely. Therefore, the movement of the CAI’s reference mirror inside the satellite is analyzed using the Hybrid Simulation Platform for Space Systems (HPS) developed by DLR and ZARM (University of Bremen). Misalignments and vibrations of the reference mirror cause an additional CAI phase shift, which introduces measurement inaccuracies. Our work examines the translational displacement, rotational misalignment and angular velocity of the reference mirror, due to forces transferred by the coupling link between mirror and satellite. This helps to compare different hybridization concepts and to improve noise and signal models for CAI accelerometers

Analyzing nicotinamide adenine dinucleotide phosphate oxidase activation in aging and vascular amyloid pathology

In aging individuals, both protective as well as regulatory immune functions are declining, resulting in an increased susceptibility to infections as well as to autoimmunity. Nicotinamide adenine dinucleotide phosphate (NADPH) oxidase 2-deficiency in immune cell subsets has been shown to be associated with aging. Using intravital marker-free NAD(P)H-fluorescence lifetime imaging, we have previously identified microglia/myeloid cells and astrocytes as main cellular sources of NADPH oxidase (NOX) activity in the CNS during neuroinflammation, due to an overactivation of NOX. The overactivated NOX enzymes catalyze the massive production of the highly reactive O−2, which initiates in a chain reaction the overproduction of diverse reactive oxygen species (ROS). Age-dependent oxidative distress levels in the brain and their cellular sources are not known. Furthermore, it is unclear whether in age- dependent diseases oxidative distress is initiated by overproduction of ROS or by a decrease in antioxidant capacity, subsequently leading to neurodegeneration in the CNS. Here, we compare the activation level of NOX enzymes in the cerebral cortex of young and aged mice as well as in a model of vascular amyloid pathology. Despite the fact that a striking change in the morphology of microglia can be detected between young and aged individuals, we find comparable low-level NOX activation both in young and old mice. In contrast, aged mice with the human APPE693Q mutation, a model for cerebral amyloid angiopathy (CAA), displayed increased focal NOX overactivation in the brain cortex, especially in tissue areas around the vessels. Despite activated morphology in microglia, NOX overactivation was detected only in a small fraction of these cells, in contrast to other pathologies with overt inflammation as experimental autoimmune encephalomyelitis (EAE) or glioblastoma. Similar to these pathologies, the astrocytes majorly contribute to the NOX overactivation in the brain cortex during CAA. Together, these findings emphasize the role of other cellular sources of activated NOX than phagocytes not only during EAE but also in models of amyloid pathology. Moreover, they may strengthen the hypothesis that microglia/monocytes show a diminished potential for clearance of amyloid beta protein

Longitudinal Plasma Metabolomics Profile in Pregnancy—A Study in an Ethnically Diverse U.S. Pregnancy Cohort

Amino acids, fatty acids, and acylcarnitine metabolites play a pivotal role in maternal and fetal health, but profiles of these metabolites over pregnancy are not completely established. We described longitudinal trajectories of targeted amino acids, fatty acids, and acylcarnitines in pregnancy. We quantified 102 metabolites and combinations (37 fatty acids, 37 amino acids, and 28 acylcarnitines) in plasma samples from pregnant women in the Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD) Fetal Growth Studies-Singletons cohort (n = 214 women at 10-14 and 15-26 weeks, 107 at 26-31 weeks, and 103 at 33-39 weeks). We used linear mixed models to estimate metabolite trajectories and examined variation by body mass index (BMI), race/ethnicity, and fetal sex. After excluding largely undetected metabolites, we analyzed 77 metabolites and combinations. Levels of 13 of 15 acylcarnitines, 7 of 25 amino acids, and 18 of 37 fatty acids significantly declined over gestation, while 8 of 25 amino acids and 10 of 37 fatty acids significantly increased. Several trajectories appeared to differ by BMI, race/ethnicity, and fetal sex although no tests for interactions remained significant after multiple testing correction. Future studies merit longitudinal measurements to capture metabolite changes in pregnancy, and larger samples to examine modifying effects of maternal and fetal characteristics